This invention relates to a door hold-open mechanism for use with door closers, and more particularly, to an electrically controlled hold-open which may selectively be released or manually overridden.
It is conventional practice to provide doors in public buildings with hydraulic or spring-urged devices for automatically urging and returning doors to their closed positions. In some circumstances, it is desirable to temporarily defeat or overcome the action of the door closer, by providing a hold-open mechanism to maintain the door in its open position. Hold-open mechanisms may be made selectively releasable, often in response to a remote sensor such as a smoke detector. Examples of patents directed to hold-open mechanisms, among numerous others, are U.S. Pat. Nos. 3,771,823, issued Nov. 13, 1973, to Schnarr, 4,506,407, issued Mar. 26, 1985, to Downey, 4,286,412, issued Sept. 1, 1981, to Stevens and 4,663,800, issued May 12, 1987 to Mettenleiter, et al..
The present invention is directed to a mechanically simple yet effective releasable hold-open mechanism of the above general type, but which provides among its advantages a secure and reliable latching action, ease of release when release is desired, and the ability to provide for an infinitely adjustable angle of door opening within a desired range of between approximately 80.degree. to 120.degree. of door opening. Other objects and advantages of the invention will be apparent.